This invention relates to a novel escalator or moving sidewalk hand rail drive mechanism.
Various escalator and moving walks structures have been described in the prior art.
Taylor, U.S. Pat. No. 3,653,484 relates to a handrail driving assembly for belt type moving passenger conveyors in which a plurality of traction providing rollers are disposed along the length of the conveyor to operate independently of each other, each deriving its motive power from the motion of the belt.
Clark, U.S. Pat. No. 3,414,109 describes the return run of a moving handrail engages a plurality of successive traction rollers, each provided with a pressure roller. A cantilever mounting of rollers provides accessibility. A coil spring mechanism is used to keep the handrail in contact with the traction rollers.
Taher et al., U.S. Pat. No. 3,779,360 pertains to a transportation device having an endless handrail driven about a closed loop by drive means which include traction and pressure rollers. The pressure rollers are biased against the handrail, opposite the traction rollers, by biasing means which includes at least one main leaf spring member. A leaf spring member is stressed from a predetermined unstressed curved configuration to a flat configuration when the handrail is disposed between the traction and pressure rollers.
Meyer et al., U.S. Pat. No. 5,307,920 discloses an escalator handrail drive system which includes a powered drive belt engaging the underneath surface of the handrail along the return path of travel of the latter. A series of pressure rollers engage the outer surface of the handrail to press the latter against the drive belt. The pressure rollers are all biased against the handrail by a single tensioning spring. The drive belt is pretensioned by an adjustable pretension spring assembly which can apply a fixed pretensioning force to the drive belt which will not substantially change irrespective of whether the handrail is being driven in the "up" direction or in the "down" direction on the escalator.
Ahls et al., U.S. Pat. No. 5,117,960 discusses an escalator or moving walkway handrail driven by a pair of linear belts which engage opposite sides of the handrail along the return path of travel thereof. The belt that engages the underside of the handrail is a powered drive belt, and the belt that engages the upper-side of the handrail is a pressure or reaction belt. Both belts are held against the handrail by a set of biased pressure rollers which urge the reaction belt against the handrail. The belts serve to convert line contact with the pressure rollers into area contact with the handrail thereby spreading out the driving forces acting upon the handrail. Ahls et al., 5,341,909 describes a direct drive wheel to handrail contact drive assembly utilizes a pair of drive rollers which contact the handrail directly. The drive rollers are powered by a single drive shaft. A pair of pressure rollers oppose the drive rollers so as to press the handrail against the drive rollers. The pressure rollers are spring biased against the handrail. The drive assembly is used to drive the handrail of an escalator or moving walkway.
Nurnberg et al., U.S. Pat. No. 5,125,494 relates to a drive pulley system provided for a handrail drive mechanism of a passenger conveyor. The system includes a pulley, with a handrail drive belt wrapped about the pulley for rotation therewith. A pair of disc-like members are disposed on opposite sides of the pulley to sandwich the pulley therebetween. The disc-like members have diameters greater than that of the pulley and are rotatable relative to the pulley, or the disc-like members may be fixed to the pulley and be fabricated of low friction material. The handrail is wrapped about the outer peripheries of the disc-like members, spacing the handrail from the drive belt, and thereby allowing differential linear movement between the handrail drive belt and the handrail due to the relative rotation between the disc-like members and the pulley, or due to slippage between the handrail and the low friction disc-like members. The system also includes an idler pulley disposed in an area between the pulley and a second pulley and about which both the handrail drive belt and the handrail drive are wrapped to impart drive to the handrail by the drive belt. The idler pulley substantially spans the area between the other two pulleys to provide a large included angle of engagement between the idler pulley, the handrail and the handrail drive belt.
Bruehl et al., U.S. Pat. No. 4,895,240 pertains to the handrail of an escalator of other passenger conveyor is driven by traction rollers which engage the handrail and also directly engage links which are connected to and drive the steps or tread of the conveyor. The handrail is biased into engagement with the traction rollers, and moves at substantially precisely the same speed as the steps or tread due to the direct connection between the step or tread drive and the handrail drive.
Hermann et al., U.S. Pat. No. 4,875,568 refers to an escalator handrail is driven by a pair or angularly offset rollers. The angular offset of the rollers causes a wedging effect at a roller nip whereby the driving force imparted by the rollers to the handrail is increased. Hermann et al discloses a spring tensioning arrangement.
German Patent Document No. 4301512A1 relates to a three-state planetary reduction gearbox for driving a coaxial handrail pulley for an escalator in which a bearing housing is bolted in the handrail drive.
The problem with prior are devices is that the handrails tend to slip with respect to the foot pieces or passenger load run which requires the passenger to release his or her grip from the handrail from time-to-time to avoid being dragged forward or backward of the place on which they are standing. The relative displacement of the handrail vis-a-vis the foot pieces can result in accidents including falls which has lead to increasing liability insurance costs. The slippage of the handrail is due to slippage in the handrail drive mechanism. The present invention presents a solution to this problem by providing a mechanism to maintain synchronous movement between the handrail and the foot pieces.